1. Field of the Invention
This invention relates to an airconditioning control system for use with an automotive vehicle.
2. Disclosure Information
The design of automotive airconditioning control systems presents a variety of problems to the engineer. For example, the temperatures at which individual passengers feel comfortable while occupying the vehicle may diverge widely. This divergence is due in some cases to external influences such as solar load, air leaks, or conduction through various surfaces within the vehicle. Comfort of individual passengers may also be affected by individual preferences and also by differences in dress. These problems are compounded within the automotive environment by low availability of space in which to place airconditioning componentry.
Further problems arise from the fact that vehicle occupants sit in close proximity to the air discharge registers. Thus the incoming airflow "blows" upon the face or other parts of the body. Some motorists object to this phenomenon, whereas others do not. It has been found, therefore, that independent control of the quantity of airflow reaching a driver and any passengers will materially increase the ability of an airconditioning system to satisfy the individual needs of the driver and passengers.
In a conventional automotive airconditioning control system, a single blower is combined with a single evaporator core and a single heater core. A control panel operated by the driver of the vehicle is set to determine blower speed, desired discharge air temperature and desired air discharge location. Typically, one or more registers are provided, which registers may be controlled by the driver and passengers to either reduce or eliminate the flow of conditioned air impinging upon either the driver or the passengers. Such systems do not, however, provide independently controllable airflows to the driver and passenger because closing or opening of the various registers will cause more or less air to be discharged from the remaining registers. In other words, the flows through the various register openings are cross-coupled. The present invention eliminates this cross-coupling without the necessity for additional blowers or heater cores or airconditioning evaporators.
Designers seeking to provide automotive airconditioning control systems capable of creating a comfortable climate for more than one vehicle occupant have developed several types of dual or multizone control systems. An example of an early dual control system is found in U.S. Pat. No. 2,860,567 in which separately operable controls are provided for a driver and passenger of a motor vehicle. This system includes a separate heat exchanger for each zone of operation and functions essentially as two separate systems.
Several examples of multizone airconditioning control systems are disclosed in U.S. Pat. Nos. 4,460,036; 4,537,245; and 4,482,009. Each of these patents describes a system having the capability for individual temperature control for two or more zones, but each lacks the ability to independently change the airflow delivered to two or more zones. More specifically, each of these systems uses a manually operated blower control which will not allow independent change of airflow rates to two separate zones of operation.
U.S. Pat. Nos. 4,426,852, 4,434,932, and 4,375,754 disclose airconditioning control systems in which the direction of flow of conditioned air is shifted depending upon which seats in the motor vehicle are occupied. Although providing selective delivery to more than one zone, these systems do not provide independent control for airflow rate to two or more zones of operation with a single blower because an increase in airflow rate for one zone at a constant blower speed will be accompanied by a reduction of airflow in all other zones.
It is an object of the present invention to provide an airconditioning control system for an automotive vehicle with the capability of supplying conditioned air at independently variable flow rates to at least two separate zones of operation within the automotive vehicle with the use of a single blower means.
It is a further object of the present invention to provide an airconditioning control system for an automotive vehicle in which not only airflow rate, but also desired discharge air temperature, and desired location of air discharge may be varied independently for at least two separate zones of operation of the vehicular climate control system.
It is yet another object of the present invention to provide an airconditioning control system which avoids cross-coupling between the airflows provided to at least two independent zones of operation within the automotive vehicle. This is particularly important during the transitions which occur when one but not all of the vehicle's occupants has called for a greater or lesser airflow rate.
It is an advantage of the present invention that independent airflow rates may be provided to at least two independently operable zones with a single air supply blower, a single evaporator core, and a single heater core.
It is yet another object of the present invention to provide an airconditioning control system for an automotive vehicle in which at least two control panels are used to provide individual inputs from a driver and passenger of the vehicle to a system having a single blower, evaporator core and heater core.